This invention relates to an indexable insert drill and more particularly to such a drill which finds particular application for drilling a laminate workpiece.
When cutting a through-bore, some indexable insert drills terminate with a slug at breakout. If the workpiece is a laminate structure or comprises several stacked workpieces, such a drill will produce a slug at breakout from each layer of material. Except for the bottommost layer of a laminate workpiece, the breakout slugs are trapped between the drill and the next adjacent layer of material. Such a trapped breakout slug tends to rotate with the drill to impede the cutting operation and may possibly cause failure and destruction of the drill. It is generally an object of this invention to provide an indexable insert drill that avoids formation of a breakout slug and is capable of a smooth transition between the layers of a laminate workpiece.